A helping hand
Over the past 150 years, our nation has lost more than 50 percent of its wetlands — areas of land frequently saturated by surface or ground water that include swamps, marshes and bogs. Although there has long been an understanding of the significance of wetlands to biological resources such as fish and game species, the importance of wetlands in cleaning water, buffering against erosion, recharging groundwater supplies and providing recreational opportunities has only recently been widely recognized.
A recent article1 has placed a value on wetlands of $9,990 to $14,785 per hectares (10,000 square meters) per year. Globally, this amounts to $9 billion per year of lost values related to lost commercial and recreational resources supported by wetlands. The need to restore wetlands' lost functions and values has prompted a major commitment of public and private time, energy and resources.
Goals of restoration
Restoration is defined as the return of an ecosystem to a close approximation of its condition prior to disturbance. Restoration's goal is to establish a self-regulating system that is integrated into the surrounding landscape. The hope is that, without human intervention, the system will evolve naturally, resilient to disturbances and maintaining itself in perpetuity. Unsurprisingly, many projects have failed to meet these goals, owing to the enormous complexity of nature's ecosystems. Also previous restoration efforts have largely been inadequately documented, providing little insight into the reasons for failure and dooming restorationists to repeat others' mistakes. This inadequacy can be attributed to the lack of funding for wetland restoration science.
Out of frustration, many restorationists are exchanging information to maximize the probability of success. New work published in scientific journals, such as Restoration Ecology and Ecological Applications, and presented at professional meetings, such as those held by the Society of Ecological Restoration, detail successes and failures.
Systematic restoration implementation
A systematic process can guide project development. A restoration project has five basic parts:
- Planning;
- Construction;
- Assessment of performance;
- Management of the system; and
- Dissemination of results.
Planning. The key element in the planning phase is to develop clear goals for the project. Goals should be simple and unambiguous, relate directly to the vision of the project and be feasible to implement. The goals are the guiding principles upon which the project is designed. Unsuccessful projects often have no goals or vague goals that provide little guidance for judging the system's performance.
The ultimate goal for restorationists is accurately predicting the rate and direction of a project's development by setting up the initial conditions that will, over a known length of time, result in a defined ecosystem condition (i.e., hit the goal for the project). However, most projects end up at a somewhat different condition than originally planned because of so many uncertainties associated with restoration.
Restorationists are shying away from the landscaper's approach that uses a wide variety of species in an elaborate planting plan, and are instead moving toward an approach that creates favorable conditions for system development. It is now becoming clear that creating fundamental geomorphologic and hydrological conditions at a site, and then letting natural processes go to work, is a more efficient method to "build" an ecosystem.
Once these fundamental conditions are established, plant and animal succession can occur naturally. This process may involve planting a specific species known to be either a hardy dominant or an early colonizer to prepare the system for later succession species. The downside to this approach is the length of time required to reach a desired state. The upside is fewer expenses in landscaping materials and labor.
The conceptual model
To help achieve the wetlands restoration goal, development of a second key element of planning is necessary — the conceptual model. A conceptual model, likely implicit in many restoration plans, should be explicitly defined. The model should contain the goal as the final outcome, the structural aspects of the system that must be developed to meet the goal and the factors in the environment that largely control attainment of the goal. For example, if the goal of the project is to restore fish in a lake that has suffered from eutrophication (i.e., overloads of nutrients), the conceptual model would be as follows:
Reduce nutrient input > clear water, increased dissolved oxygen > healthier fish.
This simple model provides much of the basis for designing the restoration project. Most systems are more complex than this and, because of this complexity, should be the subject of a careful conceptual model development effort. Development of a conceptual model forces scientists, planners and engineers to examine what they do and do not know about the system. Key questions often emerge from the exercise, which can then be addressed by directed research.
Site assessments
In planning a project, a site assessment — not to be confused with the standard Phase 1 environmental assessment as specified by the American Society for Testing & Materials — may be needed. If the site is not right, i.e., if it lacks those characteristics necessary to reach performance goals, the restoration will likely fail. For example, seagrass meadow restorations on the West coast have a long history of failure, largely because the sites are either not at the correct depth or are subject to continued disturbances. If seagrasses are not present at a site, there must be a scientific reason. A site assessment provides information needed either to design "fixes" to problems, or to reject the site as inappropriate. It is strongly recommended that sites where explanations for the absence of the desired community are not obvious have assessments performed. This can be as simple as a walk-through by competent individuals with a strong background in the ecosystem targeted for restoration or as co
mplex as sampling and experimentation.
The site assessment requires some knowledge of the physical and chemical requirements of the target restoration ecosystem. Continuing with the example of seagrasses, for an accurate assessment, one would need to know the level of light needed for growth (they are normally found in shallow aquatic areas); the salinity regime; temperature tolerances; sediment and nutrient requirements; potential susceptibility to grazers or other biological disturbances and the tolerance range for wave and current energies. The site assessment attempts to determine whether the site in question falls within the tolerance ranges for the species to be restored. If not, either changes to the site should be made (e.g., reducing nutrient loading from uplands) or the site should be rejected. However, if the seagrasses are absent from the site because of a one-time major disturbance (e.g., propeller scar) which has since ceased, seagrass restoration is possible.
The site assessment helps define the effort needed to restore a site as well as provides an increased level of confidence about the project's potential success. It also provides a better understanding of factors that should be watched in the monitoring program following the initial restoration effort.
Although a site assessment adds cost and time to a project, it is well worth the effort in the long run. Cost overruns most often result when surprises about the site are encountered during construction. For example, excavation in 1986 for restoration of the Gog-le-hi-te Marsh in Commencement Bay, Wash., uncovered a pocket of soil heavily contaminated with polychlorinated biphenyls (PCBs). The subsequent removal of this material, which was highly localized, cost approximately $100,000.
Cost estimation
In the latter stages of planning, costs are estimated relative to engineering designs and specifications. Projects can be simple and inexpensive or complex and costly. National cost reviews for wetland and aquatic ecosystem restoration projects range from $2,000 or less per acre to over $1.5 million per acre. Projects more than a few acres in size can be very costly because of engineering design and construction costs. Land acquisition can also substantially drive up the costs, even for small projects, if they are located in highly urbanized situations, such as ports.
Construction. The engineering design must have clear guidance and input from those knowledgeable about the ecosystem's requirements and tolerances. If, for example, a wetland requires water to saturate the roots and rhizomes of plants for four months in spring and early summer, the tolerances for hydrology are critical. The engineers must be aware of this and have information about the hydrology of the site to ensure that requirements are met. The more complex the project, the more interactions are needed between ecosystem scientists and engineers.
In general, projects that require less engineering (i.e., physical restructuring of the site) are more likely to succeed and persist without human intervention. Again, the site assessment helps determine the degree of physical changes needed at the site. Hence, sites requiring massive reworking often have a higher degree of uncertainty in terms of success. They may also require continued, long-term maintenance to keep functioning.
Restorationists are finding that Mother Nature can often be a major ally in the development of the ecosystem. For example, designing tidal channels for a tidal marsh is a tricky and complex undertaking — accurately predicting where channels will develop and their final morphology is impossible. A strategy that involves lowering an area's elevation slightly to encourage channel development, and then letting hydrodynamics carve the channels over several years, is becoming the preferred method for producing channel configuration. Once the channels are defined, vegetation can be planted.
Implementation. Implementation of the project is an exciting phase, similar to building a new house. It involves a lot of effort, concern, debate, decision-making, course correcting and joy. It is at this point that the public often gets involved through volunteer programs and where the energy for a restoration project reaches its peak. It is critical that the implementation be carefully carried out and monitored. Horror stories are all too common about simple mistakes (e.g., the plants were put in upside down) during implementation that become the death knell for the project. Monitoring may require a knowledgeable and responsible person to be on site daily during implementation. This person should have the authority to temporarily stop construction until an assessment from the engineering and restoration team can be made.
Assessment of performance. Post-implementation monitoring provides critical information on the performance of the restored system toward its goal. However, because it adds cost and must be conducted over time, monitoring is often minimal, or not carried out at all. Because all restoration projects are experiments, often involving a high degree of uncertainty, heavy cost commitment and high project visibility, monitoring is a key element in the process of managing the project.
Monitoring programs do not have to be costly and complex, however. As a first step, it is always a good idea to monitor a parameter indicative of the goal; reviewing the conceptual model can provide a good indication of those key factors that fall under this classification. For example, there are numerous ingenious ways to effectively monitor wetland hydrology, a major controlling factor in terms of wetland development, such as plastic pipes inserted in holes in the wetland with ground cork to show maximum water levels. Likewise, vegetation cover is often the most easily monitored component of the system and also often relates directly to the system's goals. In addition, simply keeping track of local weather through the Internet will provide key information on factors affecting both hydrology and plant growth. Taking photographs of the site from permanent points and having a site steward frequently walk the site to record unusual events are also very informative monitoring tools.
Management of the system. The site management process incorporates the concept of adaptive management, i.e., learning by doing. Because many restoration projects are driven by regulatory requirements to mitigate wetland losses associated with development projects, regulators are not particularly warm to the idea of conducting "experiments" with these projects. However, most are coming to the realization that some uncertainty does exist in restoration success and that adjustments must be made to correct problems.
Just like a physician monitoring the blood chemistry of a patient, site monitoring provides the input needed to make necessary adjustments in the treatment of, and prognosis for, the system. The progress of the system toward its goal can be reviewed at annual meetings with interested parties. Monitoring data provide the basis for any decisions made by the group. Options include:
- Do nothing if the system seems to be progressing well;
- Do something that redirects the development of the system; or
- Change the goal if it is determined through monitoring activities that the original proposed goal is unrealistic.
Dissemination of results. It is imperative to document and disseminate information on restoration projects in order to learn from others' experience. Reviews of past projects have been severely hampered by the lack of documentation, or the inability to access information easily. With the aid of the Internet and the growing requirement for accountability for public funds used in these projects, documentation and dissemination of information is improving.
Projects
There are thousands of restoration projects now underway or planned in the United States. Some of the largest and most exciting of these projects include the rebuilding of the wetlands of the Mississippi River delta and the restoration of the entire Florida Everglade ecosystem.
Under the Coastal Wetland Protection, Preservation and Restoration Act (CWPPRA), the coastal wetlands of Louisiana are also being restored. These wetlands have been lost at an alarming rate (65 square kilometers per year) over the past 100 years due to oil extraction under marshes and because sediment and nutrients from the Mississippi River have been cut off by river levees. These conditions have resulted in submergence and decay of the wetlands. Louisiana is literally losing land to the sea, along with important shell-fishing grounds.
The joint federal/state program CWPPRA, which spends on the order of $1 million per year, is diverting water and sediments from the Mississippi into the areas most in need of restoration. The results have been dramatic, with major increases in wetland vegetation and reversal of land loss. The program is not without its failures, but managers are using this information to improve future projects. CWPPRA is slated to run for 20 years incorporating an extensive monitoring network and reporting effort managed by the Louisiana Department of Natural Resources.
Deemed the largest ecosystem restoration project in the world, the estimated $7 billion restoration of the Kissimee River/Florida Everglades ecosystem is moving from the planning stages to implementation. The goal is to save the Everglades, that vast river of grass covering much of southern Florida. There is a belief that restoring the water-purifying properties of the ecosystem will also restore the declining seagrass meadows in the Gulf of Florida, to where much of the water through the Everglades flows.
The problems of the Everglades are well understood, relating primarily to restoring hydrology to the system. Hence, a large component of the planning has involved hydrological modeling. Implementation will include a massive effort by the U.S. Army Corps of Engineers to restore sinuosity in the river. The project has wide public and political support both in Florida and in Washington, D.C. It will be the biggest experiment yet in restoration science.
Conclusion
There are few greater sources of satisfaction than knowing that your project has made the world a better place. Ecosystem restoration is in its infancy, and it is a complex undertaking for which there are no comprehensive and definitive guidebooks. Only through systematic, science-based planning, careful implementation, effective monitoring and management and documentation and dissemination of results, can we make significant improvements to the restoration of wetlands.
Resources:
1 Costanza, R., R. d'Arge, R. de Groot, S. Farber, M. Grasso, B. Hannon, K. Limburg, S. Naeem, R. O'Neill, J. Paruelo, R. Raskin, P. Sutton, M. van den Belt. "The value of the world's ecosystem services and natural capital. Nature. (387): 253-260. 1997.
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This article appeared in Environmental Protection magazine, Vol. 11, No. 4, p. 36, April 2000. Photo courtesy of Ronald M. Thom, PhD.
This article originally appeared in the 04/01/2000 issue of Environmental Protection.